In the case where the ruminant is used as livestock, important factors for improving its productivity are improvement, of yield and quality of the animal product, improvement of reproductivity, and disease control. In order to address them, an antibiotic, a probiotic, an oligosaccharide, a plant extract, and the like are used. For example, an ionophore such as monensin, which is an antibiotic, has an effect of improving feed efficiency in meat production (Non Patent Document 1) and an effect of increasing milk yield in milk production (Non Patent Document 2).
However, in recent years, owing to a problem of emergence of antibiotic-resistant bacteria, addition of an antibiotic to a feed has been regulated strictly, and in Europe, the use of the antibiotic for growth promotion had been banned by January 2006. Further, there is a strong consumer's demand for safe livestock products, which are produced without using an antibiotic, and hence, a need for an alternative to the antibiotic is growing.
Therefore, uses of a plant extract and so on have been studied as technologies for the alternative to the antibiotic (Non Patent Document 3). However, many of the technologies have problems in that the effects are unstable and registration as feeds are not accepted, and have not yet been put to practical use.
It is known that cashew nut shell liquid has an antibacterial action (Non Patent Document 4) and a coccidiosis-relieving action (Patent Document 1). As for an effect of the cashew nut shell liquid on a ruminant, there is a report suggesting a methane-reducing effect in an in vitro test using anacardic acid, which is one of the components of the cashew nut shell liquid (Non Patent Document 5). Further, prevention of acidosis has been reported using ruminants (Patent Document 2). However, up to now, there have been no findings on improvement of milk productivity such as milk yield and milk quality of ruminants by the cashew nut shell liquid.
Further, a perinatal disease of cows accounts for more than half of reasons of death or disposal of milk cows and cause huge economic and mental damage on farmers. The perinatal disease is a collective term for diseases which tend to occur in a perinatal period before and after calving, such as hypocalcemia (milk fever), fatty liver, ketosis, and abomasal displacement. Of those, abomasal displacement is a disease which is characterized by displacement of the abomasum from a normal position to a left or right direction, and causes a symptom such as hypophagia. In many cases, right abomasal displacement is associated with intestinal volvulus and causes a severe symptom. In particular, this disease frequently occurs in milk cows after calving. This disease can be mainly treated only by a surgical operation and imposes a great burden on farmers because of hypodynamia of cows and an increase in medical cost.
Conventionally, abomasal displacement has been prevented or treated by the surgical operation as well as medical treatments with a probiotic (Patent Document 3), an agent containing catechins (Patent Document 4), prifinium bromide (Patent Document 5), and metoclopramide (Patent Document 5). However, these methods have stress problems to cows by intravenous or intramuscular injection, a long period for treatment (1 week or more), and a low curing rate. Further, clear preventive effects have not been shown. Hitherto, there have been no findings on prevention and treatment of perinatal diseases of ruminants by the cashew nut shell liquid.
Further, for both of beef cattle and milk cows, improvement of reproductivity is recognized as a very important problem directly linked to productivity and profitability. A period from insemination to nonlactating and calving without severe diseases is important in farmer's benefits. In the case of the milk cows, reduction of the number of artificial inseminations, reduction a feeding cost, and an increase in lifetime milk yield can be achieved by the satisfactory management of the perinatal period. In the case of the beef cattle, improvement of the number of calf and reduction of a management cost can be achieved by the smooth management of the perinatal period. They make a huge contribution to improvement of income in a farmer.
Conventionally, reproductivity has been improved not only by complete nutritional management such as securing of dry matter intake or supply of energy or proteins but also by feeding additives including vitamins such as vitamin A, vitamin D, and vitamin E, macrominerals such as calcium, phosphorus, magnesium, sodium, potassium, chlorine, and sulfur, and microminerals such as copper, cobalt, zinc, manganese, and selenium (Non Patent Document 6). Further, there is a report that addition of an unsaturated fatty acid (such as linoleic acid, eicosapentaenoic acid, or doco ahexaenoic acid) can improve reproductivity (Non Patent Document 7).
However, these reports have various problems in that planned nutrients cannot be fed by hypophagia and so on, before and after calving. And the effects in these reports are unclear because individual differences of the reproductivity are large. Therefore the problems have not been solved sufficiently. Further, there are problems at a cow group level, such as increases in the number of anestrous cows, decrease of an estrus detection rate, and decrease of a conception rate, and thus the overall animal husbandry conducts repeated trials and errors (Non Patent Document 8). Further, hitherto, there have been no findings on the improvement of the reproductivity of a ruminant by the cashew nut shell liquid.